ABSTRACT
Collagenous matrices appear differently at both the histological and ultrastructural levels in various tissues as, for example, in tendons, cartilage, and in basement membranes. Myoblasts, but not myotubes, contain significant amounts of fibronectin on their cell surface, suggesting that it could mediate their interaction with collagen. Proline analogues such as L-azetidine-2-carboxylic acid which inhibit the hydroxylation and secretion of collagen also inhibit differentiation in some systems. After transformation of chick embryo fibroblasts with Rous sarcoma virus, collagen synthesis decreases to one tenth or less. Macrophages release chemotactic factors, including fibronectin, which could stimulate fibroblasts to enter the wound area and begin repair reactions. Fibronectin mediates the attachment of many cells to collagenous and plastic substrates. Epithelial and endothelial cells leave a basement membrane which can be used to study epithelial cell function and metastatic tumor cell adhesion. Cartilage lacks fibronectin and the adhesion of chondrycotyes to collagen does not require fibronectin.
